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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 2nd Jan 2004, 5:53 pm   #1
Sideband
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Default Early days

I built a ZX80 with 1k memory and used it for a while before changing it for a ZX81. These may have been only glorified toys by todays standards but I learnt a lot from them and for many people it was the first real chance to find out how computers worked. I bought the (massive) 16k upgrade cartridge for the ZX81 and spent ages typing machine code programs. There were several adventure games available but most of these did not have graphics, just sets of instructions and then telling you where you were and if you were trapped anywhere.

My first 'real' computer was a Commodore 64 which I kept for some years and spent hours playing some quite advanced games on it.

By the 1990's I had a 286 with DOS 3 and so started the road to my current Compaq.


I still have the Commodore 64 and a VIC 20 if anyone is interested....


Rich
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Old 3rd Jan 2004, 12:14 pm   #2
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Default Re: Early days

I also started out with a ZX81, and learnt to program in BASIC on it. I had a 16k memopry addon (not the orginal Sinclair one) and a larger case with a better keyboard (well the buttons moved, but it was hardly a Cherry!).

I had a VIC20 and a Commodore 64 briefly, but found these to be primarily games machines. The BASIC was so slow that you couldn't do anything interesting (particularly if you wanted to use graphics and sound) if you wanted it to go at a reasonable speed. They'd be good for assembler programming, but I never got to grips with that.

I then had a BBC Model B, which really was (in my opinion) the best " home " system available at the time. It was fast and capable of a lot. The cassette interface worked well, and in due course I obtained a floppy drive and the relevant interface. I also had a high resolution green display which was clear in the 80 characters per line modes. I spent quite a lot of time using the BASIC on this, as well as word processing etc.

I had the BBC up until the late 80s, when I was given a Walters 286 PC with EGA display, a huge 170MB HDD and 1MB RAM (surplus to requirements at my father's work). By this point I was using 386SX systems at work, so I knew my way around PCs to some extent. I started with a " copy " of Compaq DOS 3.31 (which didn't have the 32MB drive limit) then bought MS-DOS 5 when it came out. I used Windows 3.0 then 3.1, but tended to prefer a few regular DOS applications. We were using QuickBASIC 4.5 at work at that time, so I had a " copy " on my PC too and spent a lot of time messing around with it. This served me for some time, but in due course it was upgraded as 2nd hand parts became available.

We now have two Dell P4 1.7GHz laptops and a home-made file server (based on an Intel server case and Intel server motherboard being thrown away at work) with over 200GB of mirrored drive space........

My programming is still mainly limited to BASIC, and I'm trying to get to grips with VisualBASIC 6. I have messed around with Perl a bit (out of necessity), and also used LabVIEW, Clipper (dBase language) and Forth where I used to work.
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Old 3rd Jan 2004, 11:45 pm   #3
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Default Re: Early days

Hi Paul.

Agree with everything you say about the '64. The VIC20 was given to me at the time and I found it pretty useless for anything interesting. I did manage to find some serious programs for the '64 as I was not really into games anyway...at least not the shoot-'em-up types that were popular. There was a good 3D chess program but it was a bit slow making decisions...and it did'nt like getting beaten! It had this annoying habit of resigning just before you were going in for the kill! There was also a 'Blockbusters' (remember that)? game with a bit-mapped Bob Holness which was quite fun but they all had pretty limited graphics. The only program I used with any real purpose was my astronomy guide which plotted the positions of the planets for the next 200 years. It also helped with tracking Halleys Comet during it's last return in 1986.

The cassette loader was pretty temperamental as I recall.

Oh well....back to REAL electronics now!!!


Rich.
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Old 4th Jan 2004, 1:07 am   #4
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Default Re: Early days

Yup...started with the ZX Spectrum too. I think I got fed up with it in the end and got a " Dragon " , I think. Can't remember much about that, apart from the name now though

Steve J
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Old 4th Jan 2004, 1:36 am   #5
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Default Re: Early days

If I remember, my first was a kit comprising a large-ish card, 6800, a bit of ram, LEDs and switches. My first program was machine code and played some tune or other.

Never had one of these ZX8x things, but I had a Nascom 1 (Z80, bit of RAM, video out and little else). I went thru a phase of building machine controllers out of 8080's and associated chipsets, all wire-wrap construction, and all microcoded by me. Such ground-up construction of a computer makes you appreciate a ready-made one!!

I had (still have somewhere) a Gemini multiboard (?) computer. Z80 again. I used these at work to replace my 8080 systems and they were even networked to a file server with 20 whole Mb of hard disk

All this was pre PC of course. As for the PC I have yet to progress above the Pentium IIs that act as desktop and file/web/mail server here at home, but no doubt I'll have to soon due to the cumbersom memory/resource hungry software we have to run these days... just not the same as the good old days with 32k of RAM with CP/M and Wordstar. And I still run Win98SE! (and Linux...)
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Old 4th Jan 2004, 5:19 pm   #6
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Default Re: Early days

Don't be too dismissive of simple computers. The Apollo missions flew to the moon using computers about as powerful as a Spectrum!
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Old 4th Jan 2004, 6:56 pm   #7
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Yes, but they didn't have to contend with Windows XP
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Old 4th Jan 2004, 8:40 pm   #8
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Default Re: Early days

I did my first programming on a ZX80 that was bought new in 1980, whike I was still at school (I was going to get the Science of Cambridge Mk14 (anybody got one of them?), but it took me so long to save up, that the Mk14 had been replaced by the ZX80).

In my first year of computer studies at school, our programming was coded onto bar marked cards, and sent off to the county eductional computer centre in Stafford at the end of each lesson. The next week, you got either a prinout of the results, or an " Error at Line xxxx " message, which meant you had to corrrect the relevant card, and send off two lots that week!

A little later, at school we had the ZX81 and Research Machines 380Z (it cheats at noughts and crosses!), and in my final year,we had an RM 480Z network, with a central hard drive (20MB in a 380Z box!). All of these were basic machines.

For a while in the mid 1980s, I worked for St Ivel, the dairy firm, as a computer operator, on a Datapoint mini-computer, this was a time share machine, which handled order input (Optical Mark Reader), accounts, stock control, order processing and wages (BACS system over a dial up modem). We also had a couple of early Compaq luggable PCs.

At college (late 1980s), we did most of our programming in PASCAL on a VAX cluster, which we also used for word processing and limited email (internal only). Microprocessor work was taught on the Motorola D2 kit, based on the 6800 processor, initialy, in HEX, but after a semester, you were allowed to run the assembler (run on an early XT).

When I joined my current employer (1990), I was trained on Motorola 68000 (horrible machine code - no structure), Z80, and DEC PDP11 series, which I still use.

I do little or no programming now, though I have a couple of projects in mind which will need me to dust off my skills, though it will probably be in Visual Basic now.

Jim.
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Old 4th Jan 2004, 9:06 pm   #9
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Default Re: Early days

Anyone remember Commodore PET? They were just before my time (more Acorn Electron, Commodore VIC 20 me). I remember them as the iconic computer design with integrated green screen and nice ergonomics. I see them on Ebay for £100 or so occasionally. If I had the space....
I took part in a Christams quiz at work. For my question I took in a ZX81, and asked:
" My computer at home has a 160GB hard disk. How many times more memory has it than this (RAM)? "
The juniors about 10y younger than me were most amused!
Kneale
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Old 5th Jan 2004, 1:51 pm   #10
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Default Re: Early days

Hi Kneale

I only remember the PET in as much as I used to use one at work. It was considered very state of the art in the mid '80s. We used to repair the Prestel (Viewdata) terminals for businesses and often had to get past passwords and other codes so that we could work on them. The PET was connected to a modem and we would call it up and it would interrogate the terminal and give a printout of the fault problem. After repair, we would call the PET again and it would run a diagnostic program on the terminal and give it a clean bill of health (or otherwise)! In order for us to work on the terminal it would override the password. I used to have a copy of the program for doing this, all in BASIC and on cassette!

Rich
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Old 5th Jan 2004, 3:50 pm   #11
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Default Re: Early days

My first computer was a second hand ZX81 which I had for a couple of years and sold on that guy then sold it to the original owner who still has it After the ZX81 I bought a new TI99/4a the first true 16 bit machine it had a very powerful version of basic.The 9900 processor was also used to control cruise missiles I eventually joined the user group committee as technical coordinator and spent many happy years experimenting and writing articles for the user group magazine until we eventually graduated to a PC (not necessarily an upgrade ) started with 386 then 486 and currently am running a pentium 650 Mhz laptop which I do quite like
but even that is stating to show it's age

Mike
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Old 6th Jan 2004, 10:06 am   #12
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Default Re: Early days

Jim

I'm surprised by your comment on the 68000. Is your issue with the assembler syntax or the actual machine code produced?
I find the 680x0 series very straightforward to program in assembly language as it has plenty of registers and addressing modes and few restrictions on use of these in instructions. It's like the PDP-11 but with 32 bit registers and more of them, more instructions and more addressing modes.
Now, comparing the 680x0 to the x86 instruction set that lives on in today's Pentiums etc.....

John
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Old 6th Jan 2004, 2:07 pm   #13
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Default Re: Early days

JJL,

my issue is with the actual HEX code - the assembler is fine.

There seems to be no logical structure to it, where as the 6800 was logical - I suspect that extra instructions were added to the 6800 set for the additional functions of the 68000.

If you want logical machine code, then the PDP11 is a great example, all instructions being made up in the same way, so yo get something like:

<instruction><addressing mode><offset>

apologies if I have this the wrong way round, I don't have the book to hand.

This means that you only use a limited number of codes, the code for the addressing mode being the same for each instruction, which makes manual coding quick and (relativly) easy.

Jim


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Old 6th Jan 2004, 6:22 pm   #14
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Default Re: Early days

Jim

I see where you're coming from.

I imagine that the PDP-11 has logical looking machine code as when it was introduced, the instruction decode logic & / or microcode ROM had to be small and simple for cost, speed, power and space reasons. All very important when a CPU comes in a large rack containing ten or so boards full of TTL ICs. As far as I know, the original PDP-11 didn't have microcode ROM, the decode being performed by hardwired logic.
When CPUs became VLSI devices, these considerations were still important but much less so.
BTW, 68000 machine code is really nothing like that of the 6800, all 68000 instructions are a multiple of 2 bytes i.e. a 16 bit word in length whereas many instructions for Motorola 8 bit CPUs were 1 byte. As an example, the hex code for the 6800 NOP instruction is 01, for the 6809 it is 12 and for the 68000 it is 4E71.

I don't have an anorak, honest

John
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Old 14th Jan 2004, 11:34 pm   #15
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Default Re: Early days

Yes, from memory, the early PDP11s were all built from discretes. Mind you, they may have had crude microcode decoders from day one. The PDP11 code set goes back to the PDP8 and before and these systems were descretes.

The nicest recreation of an early system was done by the University of Manchester. They built a replica of the MU1 which is now in the Manchester Science and Technology Museum. As part of the celebrations (50 years since they built the original I think) they published a software simulation of the original system which worked a treat. They also ran a competition for the most innovative code. An egg timer won if I recall correctly.

I cut my teeth on Fortran on a PDP11 and a Cyber72 at university in Manchester. The most fun I've had is split between real time assembly language on a PDP11 and building and programming microcontrollers.

Cheers

Robin
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Old 15th Jan 2004, 3:42 pm   #16
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Default Re: Early days

For those interested in the PDP-11 & associated DEC bits & pieces, take a look at this link

http://www.psych.usyd.edu.au/pdp-11/

John
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Old 16th Jan 2004, 10:06 pm   #17
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Default Re: Early days

Also look in the PDP Unix Preservation soc. Links from the previous entry. There are a lot of nice PC simulators for PDPs out there which will run most of the operating systems used.

Robin
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Old 16th Jan 2004, 11:16 pm   #18
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Default Re: Early days

Jjl,

the PDP site is excellent, though a bit too much like being at work!

Jim.
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